Chris Cornell, the lead singer of Soundgarden and Audioslave, passed away from suicide late Wednesday night. The 52-year-old musician was found dead in his hotel room in Detroit after a Soundgarden performance at the Fox Theatre, People reports. “His wife Vicky and family were shocked to learn of his sudden and unexpected passing,” Cornell’s rep, Brian Bumbery, said in a statement.

We can’t possibly know all the factors that lead someone to suicide. Cornell’s family suspects the side effects of his prescription drugs may have played a role; Cornell told his wife he had taken “an extra Ativan or two” that night, according to People.

But we do know that this time of year can be especially difficult for people grappling with mental health issues. Sadly, research shows there is a peak in suicides in the spring.

According to the Centers for Disease Control and Prevention, suicide rates spike in the spring and to a lesser extent in the fall—not around the holidays as everyone suspects. And suicides in general have increased 24% between 1999 and 2014, according to a CDC report released last year.

The uptick begins in early April and late May. Why? The seasonal brightness may have something to do with it: In a 2016 op-ed in The Washington Post, Harvard professor of psychology Matthew Nock cited a study published in JAMA Psychiatry that found that as hours of sunlight increased, so did the risk of suicide. "The authors speculate that sunlight could boost energy and motivation, thus giving people who are depressed the ability to take action and make a suicide attempt," he wrote.

And some researchers are looking at suicide rates at times of high-pollen counts compared with less pollen, theorizing that the increase might be due to increased anxiety or aggression related to inflammation.

Another possible culprit for feeling low this time of year is seasonal affective disorder: It's typically associated with winter, but warmer temperatures and brighter days aren't always enough to lift the blues. What's more, seeing cheery people all around you is a constant reminder that others are having a good time when you aren't, says Michelle Riba, MD, professor and associate director of the University of Michigan Comprehensive Depression Center.

There's also a phenomenon called summertime depression, she adds, which means people may start to get sad when spring arrives. “We don’t really know why. It may be hormonal for women, and there are theories related to melatonin production, but we’re not sure,” she says.

And then there are social influences that can bring a person down: This time of year, "people go on vacations, and some groups may be disbanding for the season," explains Dr. Riba. "So there may be less structure and a sense of support in place.” Meanwhile, you're watching friends enjoy those picture-perfect vacays on Facebook or Instagram. “You wish well for everybody but sometimes you can experience jealousy and envy when you see this," says Dr. Riba. Especially if you happen to be struggling with challenges in your own life, like a bad breakup or financial concerns.

When to seek help

If you think you might at risk for depression, keep a journal of your feelings, says Dr. Riba. Believe it or not, it’s easy to forget how you’re feeling day to day, she explains. Record things like mood, changes in appetite, sleep issues, concentration, and energy problems, and feelings like hopelessness and worthlessness. If you consistently feel this way for two weeks or more, see your doctor. It may be depression, but other medical issues (like a low thyroid, for example) can cause similar symptoms, and it’s best for your doctor to rule those out.

“A lot of times people don’t really know what they’re experiencing is depression. You just might not feel well and not understand why,” says Dr. Riba. She explains that depression can manifest as physical symptoms, like GI problems, headaches, or trouble sleeping. So be on the lookout for those as well.

Bottom line: “If you think something may be wrong, seek help,” says Dr. Riba. “People think that somethinghad to have happened to have depression, or that you can will yourself out of it, but that’s not true. It’s a biological process—and there shouldn’t be any stigma associated with taking care of yourself.”